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P. L. Read, L. Montabone, S. R. Lewis, P. R. Barker (University of Oxford), MGS TES Team
The Mars Global Surveyor spacecraft has been in orbit around Mars since 1997, and during its ongoing mapping phase has produced a climatology of more than two complete Martian years of atmospheric temperature profiles and dust opacity up to altitudes of 40- 60 km, using the onboard Thermal Emission Spectrometer (TES). We have assimilated these data into a general circulation model (GCM) of the Martian atmosphere, in order to produce a time-evolving 4-D picture which is as close as possible to a synoptic record of the real atmosphere. One important issue is the validation of the assimilated results versus an independent source of data. For this purpose, we use the temperature profiles retrieved from the radio occultation measurements with the ultra-stable radio oscillator aboard Mars Global Surveyor. We show that, in general, temperature profiles from the data assimilation experiment are closer to radio occultation profiles than those from an independent GCM, in particular during the polar night, in regions where the GCM is thought to be less accurate. There are uncertainties in converting the measured TES dust opacities in the infrared to appropriate average values in the visible for the GCM and various ratios of the opacities in these two wavebands are also tested by comparison with radio occultations. A number of studies are under way using this validated dataset and will be briefly presented, including an evaluation of the interannual variability of regional and global dust storms (including the global dust storm of 2001) and their effects on various tidal modes. We gratefully acknowledge the contributions of Drs M. D. Smith and B. J. Conrath for their generous provision of TES retrievals, and financial support from the UK Particle Physics and Astronomy Research Council.
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The author(s) of this abstract have provided an email address for comments about the abstract: p.read1@physics.ox.ac.uk
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.